Summary :
Objectives: Radio-induced sarcoma is known to occur several years following bone irradiation especially when this treatment is combined to high dose chemotherapy regimens prior to allogeneic haematopoietic stem cell transplantation (HSCT) in very young children. However, little is known about the stimulus of aggressive bony surgery in the development of these tumours. Materiel and methods: We report the case of a young girl in whom dental extraction was rapidly followed by the occurrence of a localized tumour 11 years after allogeneic haematopoietic stem cell transplantation using total body irradiation (TBI) for a haemophagocytic lymphophistiocytosis (HLH). Results: This tumour involved tooth socket and all the right side of the mandible and was diagnosed as an osteogenic osteosarcoma of the zygomatic bone. Conclusion: This tumour had the characteristics of a radio-induced sarcoma. Thanks to the very short time between the dental extraction and the occur­ren­ce of the osteosarcoma at the same location, we discuss the role of the dental extraction as a trigger of osteo­sarcoma develop­ment.